I intend predefining it. But since I create those levels through code, it can be tweaked to have more complex rules. The limiting factor is the texture sprite since I can't make it larger than it is and it's pretty stuffed already. So I can't add new spaceships right now unless I do some effort to save texture space (e.g. mirroring springs to reduce the number of sprites per space ship, reducing color depth, etc).
Compiling shouldn't be too difficult. I use a bunch of Lua scripts to do some pre build steps, but this is only needed when images are updated. The td2play framework (included as a submodule) I maintain contains the additional code needed that needs to be copied into the MicroVektoRoids folder. Once it's all there, the .ino file can be opened and compiled for the device.
The project also contains a simulator where I simulate the game on a PC - I simply mimic the API calls required to display the tiny screen content. But compiling this would require you to have a similar setup as I have here (windows + codeblocks + Lua (+libs)).